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The
Cutting Edge of High-Temperature Composites
Industrial Productivity and Manufacturing Technology
Originating Technology/NASA Contribution
NASA’s Ultra-Efficient
Engine Technology (UEET) program was
formed in 1999 at Glenn
Research Center to manage an important
national propulsion program for the Space Agency. The UEET
program’s focus is on developing innovative technologies
to enable intelligent, environmentally friendly, and clean-burning
turbine engines capable of reducing harmful emissions while
maintaining high performance and increasing reliability.
Seven technology projects exist under the program, with each
project working towards specific goals to provide new technology
for propulsion. One of these projects, Materials and Structures
for High Performance, is concentrating on developing and
demonstrating advanced high-temperature materials to enable
high-performance, high-efficiency, and environmentally compatible
propulsion systems. Materials include ceramic matrix composite
(CMC) combustor liners and turbine vanes, disk alloys, turbine
airfoil material systems, high-temperature polymer matrix
composites, and lightweight materials for static engine structures.
Partnership
Hyper-Therm High-Temperature
Composites, Inc. (Hyper-Therm
HTC), is a worldwide leader in producing high-temperature
ceramic composite materials. In the mid-1990s, the Huntington
Beach, California-based company created a silicon-doped boron
nitride (BN) fiber coating for advanced CMCs. This development
was geared towards demanding applications that require increased
durability and longevity, as well as demanding environments,
such as space.
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Hyper-Therm
High-Temperature Composites, Inc., is developing
advanced composite materials for a variety of high-temperature
aerospace applications, including hypersonic aircraft
thermal structures and advanced rocket propulsion
thrust chambers. |
By participating in NASA’s Small
Business Innovation Research (SBIR) program with Glenn, Hyper-Therm HTC is helping the
UEET program reach its goals to “develop and hand off revolutionary
turbine engine propulsion technologies that will enable future-generation
vehicles over a wide range of flight speeds.” Hyper-Therm
HTC’s ceramic composites are also being evaluated by other
NASA programs that require improved materials for next-generation
launch and flight vehicles.
Additionally, Hyper-Therm HTC was contracted (SBIR) by Glenn’s
neighbor to the south, Marshall
Space Flight Center, to devise
a unique and cost-effective methodology for manufacturing
axisymmetric ceramic composite structures. According to the
company, this project helped to facilitate the world’s first
actively cooled, continuous fiber-reinforced silicon carbide
(SiC)-matrix composite thrust chambers for liquid rocket
propulsion systems. These propulsion devices were designed
to be cooled with cryogenic liquid hydrogen, to provide protection
from severe, high-temperature combustion environments (greater
than 6,500 °F liquid hydrogen/oxygen). Hot-fire testing of
the devices was performed
by Glenn.
By working with NASA’s Glenn and Marshall centers, as well
as other branches of government, Hyper-Therm HTC was able
to further develop and optimize its composite technology
for government and commercial aerospace, plus commercial
industrial applications.
Product Outcome
Hyper-Therm HTC has experienced sales in excess of $4 million,
thanks to its advanced composite materials, coatings, and
components. The technology has been folded into everything
from hypersonic airframe and thermal re-entry structures,
to turbine disks, laser mirror substrates, heat-engine devices,
ballistic penetrators, micro-rotary cutting tools, and free-standing
refractory metal components for nuclear, medical, and materials
research applications.
The cutting-edge composites are produced via isothermal/isobaric
and forced-flow chemical vapor infiltration (CVI) processing
techniques. The company’s most popular high-temperature structural
material systems are composed of carbon and SiC fiber reinforcements
in a CVI SiC matrix. Available fiber coatings include silicon-doped
BN, pyrolytic BN, pyrolytic carbon (PyC), and duplex PyC-B4C,
all of which have been developed to impart an optimum balance
of strength, fracture toughness, and strain-to-failure.
For applications demanding increased durability and life
in aggressive environments, Hyper-Therm HTC offers its multilayer
SiC fiber coating system and its pseudo-porous SiC system.
The multilayer fiber coating system is composed of very thin
(about 100 nanometers), weakly bonded layers of stoichiometric
SiC and was developed to mitigate the inherent problems of
oxidation and moisture instability plaguing currently available
PyC and BN fiber coatings. (In its work with NASA, the company
achieved a hundredfold improvement in moisture stability
over standard, low-temperature-derived BN fiber coatings.)
The pseudo-porous fiber coating system is composed of a thin
(less than 1 micrometer), breakable monolayer network of
porous SiC—also developed to mitigate the associated problems
with PyC and BN.
Looking ahead, the stirring demand for stronger-but-lighter,
high-temperature, cost-effective materials will fortify Hyper-Therm
HTC’s business opportunities in existing markets, as well
as new ones.
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